Mysterious craters found in the bottom of Lake Michigan

With a maximum depth of 925 feet, the expansive waters of Lake Michigan have always held a sense of mystery and intrigue. Recent research expeditions have revealed a new puzzling surprise: a series of huge craters scattered across the bottom of the lake, which were first noticed in 2022.

The craters were initially discovered during a mission to map the lakebed inside of a protected sanctuary that has been the site of many shipwrecks. These peculiar circles appeared on the sonar images, hinting at natural formations rather than anything human-made.

“Any kind of new discovery in the Great Lakes is exciting,” said Russ Green, who led the mapping project. “But these features really stand out – they are in deeper water and weren’t known before, as far as we can tell.”

Brendon Baillod, a dedicated shipwreck hunter, also spotted the circles while searching for a sunken freighter. He was convinced the circles were craters.

“There were dozens of them in our search grid,” said Baillod. “Most were 500 to 1,000 feet in diameter and of irregular shapes.”

Hidden craters in Lake Michigan

After processing data from the initial mapping project, Green and Baillod reached out to scientists at the National Oceanic and Atmospheric Administration’s (NOAA) Great Lakes Environmental Research Laboratory (GLERL) for expertise.

The teams joined forces to investigate the mysterious circles further. In 2022, they conducted a detailed survey using a remotely operated vehicle, establishing each circle as a natural, enormous crater. 

Their tally reached approximately 40, with all of the craters extending southwards from a point southeast of Sheboygan, Wisconsin towards Port Washington.

Steve Ruberg, a GLERL researcher, described the craters as “perfect, little circles” on the lakebed. The team, however, believes that there may be more craters hidden in the depths of Lake Michigan.

Sinkholes or craters?

These formations bear a striking resemblance to sinkholes previously found at the bottom of Lake Huron, which borders Michigan and Canada. 

Sinkholes typically form when groundwater dissolves bedrock, causing the top layer to collapse. Given Lake Michigan’s limestone base, which is susceptible to dissolution, the consensus leans towards these features being sinkholes.

However, some researchers, such as Baillod, prefer the term craters until more empirical evidence surfaces.

“I think they might be more accurately called craters, which have formed in the deep bottom sediment due either to water upwelling from below or trapped hydrocarbon offgassing,” said Baillod.

The recent survey did not show any signs of water escaping from the holes. This suggests that groundwater is circulating beneath the lakebed. 

Implications of the craters

Submerged life thrives in these craters, with small fish, freshwater shrimp, and invasive quagga mussels “doing their thing in the dark down there,” said Ruberg.

The exact implications of these craters for Lake Michigan and its ecosystem are not yet clear. Nonetheless, there is an air of anticipation and curiosity among the researchers. 

“We’ll be exploring them for years to come to learn more, and sort out how they got there and what role they play in Lake Michigan’s ecosystem,” said Green.

Significance of Lake Michigan

Lake Michigan is the only Great Lake entirely within U.S. borders, and stands as a vital pillar of North America’s environmental and cultural heritage. 

Spanning over 22,000 square miles, it touches four states – Wisconsin, Illinois, Indiana, and Michigan – and nurtures a rich and complex ecosystem. 

Native species such as lake trout and whitefish thrive here, while invasive quagga mussels challenge the lake’s ecological balance.

Shaped by glaciers some 10,000 years ago, the lake’s limestone basin tells the story of a dynamic geological past. 

Future exploration of the Great Lakes

The recent Lake Michigan discoveries, including large craters on its lakebed, are shedding new light on its ancient formation and evolution and offering exciting clues about how this massive freshwater body came to be.

Lake Michigan’s importance extends beyond its geology. It serves as a lifeline for millions, supporting recreation, commerce, and acting as a crucial source of freshwater. 

The mysteries hidden in the depths of Lake Michigan highlight its dynamic and ever-changing nature, and there is still much more to learn. In fact, across all five Great Lakes collectively, only about 15 percent of the lakebed has been mapped in high resolution.

Scientists have said that we know more about the surface of Mars than the floor of the Great Lakes.

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